1. Field of the Invention
This invention relates to portable optical scanners for reading indicia of varying light reflectivity and, more particularly, to a portable optical scanning system having the capability to transmit and/or receive information over one or more radio or infrared (IR) frequencies, and optionally housing the light emitter and reflected light detecting elements in separate unconnected housings that are adapted to be worn by a user or attached to an article of clothing worn by a user.
2. Description of the Related Art
Various optical readers and optical scanning systems have been developed heretofore for reading indicia such as bar code symbols appearing on the label or on the surface of an article. The symbol itself is a coded pattern of indicia comprised of, for example, a series of bars of various widths spaced apart from one another to bound spaces of various widths, the bars and spaces having different light reflecting characteristics. The readers in scanning systems electro-optically transform the graphic indicia into electrical signals, which are decoded into alphanumeric characters that are intended to be descriptive of the article or some characteristic thereof. Such characteristics are typically represented in digital form and utilized as an input to a data processing system for applications in point-of-sale processing, inventory control and the like. Scanning systems of this general type have been disclosed, for example, in U.S. Pat. Nos. 4,251,798; 4,369,361; 4,387,297; 4,409,470; 4,760,248; 4,896,026, all of which have been assigned to the same assignee as the instant application. As disclosed in the above patents, one embodiment of such scanning systems includes, inter alia, a hand held, portable laser scanning device supported by a user, which is configured to allow the user to aim the scanning head of the device, and more particularly, a light beam, at a targeted symbol to be read.
One type of portable prior art scanning device is shown in FIG. 1. Conventionally, the device includes a hand mounted scanning unit 200 which includes an optical scanner. The optical scanner conventionally has a light generator, such as a laser diode, for producing a light beam which is scanned across the target symbol. The scanner unit 200 also conventionally includes a photodetector for detecting the reflection of light from the light beam off symbol and for producing an electrical signal corresponding to the detected light and representative of the symbol. The scanning unit may be activated by a triggering mechanism, such as a movable trigger switch or by triggerless means, for example, using active or passive photosensoring.
A battery pack 202 is also mounted to the user 206 and provides power to the scanning unit 200 through cable 208. Module 204 which might typically include signal processing and data storage subsystems is mounted to the user's wrist or arm opposite the hand on which the scanning unit 200 is mounted. As shown, the scanning unit 200 is mounted on the user's right hand and the module 204 is mounted on the user's left wrist, however the side of the body upon which each is located could be reversed if so desired. Alternatively unit 200 and module 204 could be supported by the hand and arm on the same side at the user's body, for example, the right hand and arm. The module 204 is also connected to battery pack 202 by cable 202 which facilitates the transmission of electricity to the power module 204. Cables 208 and 208 also serve as a conduit for a communications link between scanning unit 200 and module 204. Signals generated by the photodetector in scanning unit 200 are transmitted to module 204 via this communication link for processing and/or storage.
The light source in a laser scanner bar code reader is typically a gas laser or semiconductor laser. The use of semiconductor devices as the light source is especially desirable because of their small size, low cost and low voltage requirements. The laser beam is optically modified, typically by an optical assembly, to form a beam spot of a certain size at the target distance. It is preferred that the cross section of the beam spot at the target distance be approximately the same as the minimum width between regions of different light reflectivity, e.g., the bars and spaces of symbol. Bar code readers have been proposed with two light sources to produce two light beams.
Bar code symbols are formed from bars or elements typically rectangular in shape with a variety of possible widths. The specific arrangement of elements defines the character represented according to a set of rules and definitions specified by the code or "symbology" used. The relative size of the bars and spaces is determined by the type of coding used as is the actual size of the bars and spaces. The number of characters (represented by the bar code symbol) is referred to as the density of the symbol. To encode the desired sequence of the characters, a collection of element arrangements are concatenated together to form the complete bar code symbol, with each character of the message being represented by its own corresponding group of elements. In some symbologies, a unique "start" and "stop" character is used to indicate when the bar code begins and ends. A number of different bar code symbologies exist, these symbologies include UPC/EAN, Code 39, Code 128, Codeabar, and Interleaved 2 of 5 etc.
In order to increase the amount of data that can be represented or stored on a given amount of surface area, several new bar code symbologies have recently been developed. One of these new code standards, Code 49, introduces a "two dimensional" concept for stacking rows of characters vertically instead of extending the bars horizontally. That is, there are several rows of bar and space patterns, instead of only one row. The structure of Code 49 is described in U.S. Pat. No. 4,794,239, which is hereby incorporated by reference. Another two-dimensional symbology, known as "PDF417", is described in U.S. Pat. No. 5,304,786.
Still other symbologies have been developed in which the symbol is comprised of a matrix array made up of hexagonal, square, polygonal and/or other geometric shapes to form a symbol. Such symbols are further described in, for example, U.S. Pat. No. 5,276,315. Such symbols may include Vericode.TM., Datacode.TM. and UPScode.TM.. Prior art FIGS. 18A-18C depict known matrix and other type symbols.
In the laser beam scanning systems known in the art, the laser light beam is directed by a lens or other optical components along the light path toward a target that includes a symbol on the surface. The moving-beam scanner operates by repetitively scanning the light beam in a line or series of lines across the symbol by means of motion of a scanning component, such as, the light source itself or a mirror disposed in the path of the light beam. The scanning component may either sweep the beam spot across the symbol and trace a scan line across the pattern of the symbol, or scan the field of view of the scanner, or perform some condition thereof.
Other conventional scanning systems require the physical movement of the scanning unit by the user to obtain a reading from the targeted symbol. For example, pen computers as shown in prior art FIG. 9 have a pen 302 associated with the computer module 300.
Bar code reading systems also include a sensor or photo detector which detects light reflected or scattered from the symbol. The photo detector or sensor is positioned in the scanner in an optical path so that it has a field of view which ensures the capture of a portion of the light which is reflected or scattered off the symbol. An electrical signal corresponding to the detected light is generated. Electronic circuitry and software decodes the electrical signal into a digital representation of the data represented by the symbol that has been scanned. For example, the analog electrical signal generated by the photo detector is converted by a digitizer into a pulse modulated digital signal, with the widths corresponding to the physical widths of the bars and spaces of a scanned bar code symbol. The digitized signal is then decoded, based on the specific symbology used by the symbol, into a binary representation of the data encoded in the symbol, and subsequently to the alphanumeric characters so represented.
The decoding process of known bar code reading system usually works in the following way. The decoder receives the pulse width modulated digital signal from the digitizer, and an algorithm, implemented in the software, attempts to decode the scan. If the start and stop characters and the characters between them in the scan were decoded successfully and completely, the decoding process terminates and an indicator of a successful read (such as a green light and/or an audible beep) is provided to the user. Otherwise, the decoder receives the next scan, performs another decode attempt on that scan, and so on, until a completely decoded scan is achieved or no more scans are available.
Such a signal is then decoded according to the specific symbology into a binary representation of the data encoded in the symbol, and to the alphanumeric characters so represented.
Systems have been developed which incorporate optical indicia reading capabilities in pen computers of the type shown in FIG. 7. Typical of these conventional systems are those shown in prior art FIGS. 8 and 9.
In the FIG. 8 system, the computer module has been modified to include a scanning unit 304 which generates a light beam which scans the targeted symbol 306. The scanning unit 304 also includes a photodetector which detects the reflection of light from the symbol and generates an electrical signal representing the scanned symbol 306. The electrical signal may be processed and/or stored in the computer module 300. Module 300 may also include a touch screen display, 308 for inputting data to the system and/or displaying the data representing the symbol.
In the FIG. 9 system, the pen computer has been modified such that pen module 302 includes a scanning unit 312 which generates a light beam which scans the targeted symbol 306 by physically moving the pen 302 across the target symbol 306. The scanning unit 312 also includes a photodetector which detects the reflection of light from the symbol and generates an electrical signal representing the scanned symbol 306. The electrical signal is transformed into a radio frequency, infrared, acoustic or other modulated wireless communication signal and transmitted by transmitter 312 to the computer module receiver 314. The received signal may be processed and/or stored in the computer module 300. Module 300 may also include a touch screen display, 308 for inputting data to the system and/or displaying the data representing the symbol.
Moving-beam laser scanners are not the only type of optical instrument capable of reading symbols. Another type of reader is one which incorporates detectors based on charge coupled device (CCD) technology. In such prior art readers the sides of the detector are typically smaller than the symbol to be read because of the image reduction by the objective lens in front of the CCD. The entire symbol is flooded with light from a light source such as a light emitting diode (LED) in the scanning device, and each CCD cell is sequentially read out to determine the presence of, for example, a bar or a space.
The working range of CCD scanners is rather limited as compared to laser based scanners and is especially low for CCD based scanners with an LED illumination source. Other features of CCD based scanners are set forth in U.S. patent application Ser. No. 08/041,281 which is hereby incorporated by reference, and in U.S. Pat. No. 5,210,398. These references are illustrative of the earlier technological techniques proposed for use in CCD type scanners to acquire and read indicia in which information is arranged in a two dimensional pattern.
Various systems, in addition to those conventional systems described above, have been proposed to improve the ease of use of optical scanning systems. Such systems have included miniature optical scanning modules which include light emitters and detectors which are mounted on a hand. These systems have also included a separate module mounted on the body or arm or wrist of a user with a wire communication link to the optical scan module. Such systems have also included wireless communication devices to allow communications between the second module and a base station, typically using radio frequency communications. However, such systems are either cumbersome, in that they require the user to wear a vest or belt or other body mounting apparel or require the use of a restrictive hand mount. One such system requires the use of a glove in which the wire for communications between the optical scan module and a second module are transmitted. Further, systems which require only a hand mounted optical scan module and wrist/arm mounted second module have had capacity limitations which limit the amount of processing and data storage which can be performed by the portable modules.
As noted above, pen computers have also been proposed for use in optical scanning applications. However, locating the optical scan module in the computer module may be ergonomically disadvantageous since it may be difficult for the user to orient the computer module in the necessary direction in order to get a satisfactory reading of the indicia. Incorporating the optical scan module in the pen module requires a communications line to transmit a signal representing the indicia to the computer module. Additionally, incorporating the optical scan module with both light emitting and light detecting devices in the pen module causes an increase in the physical size and weight of the pen. It will be understood that these size and weight increases are caused by both the additional components and the battery cells required to power them.
Thus, there remains a need for a portable optical scanning system in which all body mounted components can be mounted on the hand, wrist or arm of a user and do not require a vest, glove or other apparel or restrictive mounting mechanisms to be worn by the user. There also remains a need for a totally wireless body mounted portable optical scan system and even more preferably one which has only a hand mounted optical scan module and wrist or arm mounted second module, and is capable of transmitting and receiving data from a base station. A still further need exists for a portable optical scanning system which is ergonomically more acceptable to users.
It is a general object of the present invention to provide an improved portable indicia reader.
Thus, it is an object of the present invention to provide a portable optical scanning system which is more comfortably mounted on the user's body.
It is a further object of the invention to provide a portable optical scanning system which can be mounted on the user without the need for a vest, glove or other restrictive apparel being worn by the user.
It is a still further object of the present invention to provide a portable optical scanning system which does not require wires between system modules.
It is another object of the present invention to provide a portable optical scanning system which can be entirely mounted to either the right hand and wrist/arm or the left hand and wrist/arm.
A still further object of the invention is to provide a portable optical scanning system with improved ergonomics.
It is also an object of the invention to provide a portable optical scanning system capable of reading indicia of different symbology types including indicia comprised of a matrix array of geometric set shapes such as UPSCode.TM..
Additional objects, advantages and novel features of the present invention will become apparent to those skilled in the art from this disclosure, including the following detail description, as well as by practice of the invention. While the invention is described below with reference to preferred embodiments, it should be understood that the invention is not limited thereto. Those of ordinary skill in the art having access to the teachings herein will recognize additional applications, modifications and embodiments in other fields which are within the scope of the invention as disclosed and claimed herein and with respect to which the invention could be of significant utility.